Linear thinking requires using pre-planned processes, working with systems and machines. We are trained to use these systems without understanding them. We can start to think that we need not and cannot understand how systems work, but even things that can be hard to make can be easy to understand. We are not taught a comprehensive method for taking existing things apart to see how they are made to work. We take the existing components for granted. When we use products, machines, and processes, we are not aware of the parts. The human mind filters out what is expected and taken for granted.